PROJECT SUMMARY/ABSTRACT A majority of hospitals and ambulatory practices now use federal government incentivized electronic health records (EHRs). Problematically, the patient information stored within EHRs is not easily shared or combined across different vendor products, thereby limiting their usefulness for clinical care and business operations. To overcome this challenge, health systems are using Enterprise Health Information Exchange (HIE) to link the EHRs of affiliated providers, hospitals, and medical trading partners into their own information sharing networks. Unfortunately, Enterprise HIE is growing without evidence of its impact on the structure of health care markets and the delivery of care. Health systems hope better access to information through Enterprise HIE will lead to higher quality of care. Alternatively, a health system controlled information sharing network could alter referral patterns, market shares, and individual provider's approaches to information exchange. The objective of this proposal is to understand the potential impact of Enterprise HIE on the care and services delivered to different patient populations in local markets. Aim 1, Quantify the association between Enterprise HIE and hospital performance, leverages preliminary analyses and a 5-year national longitudinal sample of more than 2,000 hospitals. The aim tests the hypothesis that Enterprise HIE is associated with lower 30-day readmissions rates. Aim 2, Quantify the effect of Enterprise HIE adoption on local market competition, tests the hypothesis that Enterprise HIE is associated with increases in market share by comparing hospitals with Enterprise HIE to those without over time. This aim will use a 5-year panel of more than 800 hospitals from 12 states included in AHRQ's Healthcare Cost and Utilization Project State Inpatient Databases. Analyses will be stratified by payer type: privately insured, Medicare (fee for service & managed care), and Medicaid (fee for service and managed care). Aim 3, Determine if Enterprise and community HIE are competing approaches to information exchange, combines hospitals' Enterprise HIE status with a validated inventory of community HIE participation. Enterprise HIE supports the sharing of patient information with a narrow set of affiliated providers. In contrast, community-based HIE efforts are collaborative entities that strive to share patient information across all providers in a geographic area. This aim tests the hypothesis that hospitals participating in Enterprise HIE will be less likely to participate in community HIE efforts. This proposed analysis of secondary data is significant, because the US has invested billions on interoperable health information technologies and made the electronic exchange of patient information between different providers a national priority. Enterprise HIEs are an important avenue towards realizing the US' information exchange goals. This proposal is innovative, because it extends the evidence base into a new and rapidly disseminating technological intervention and examines both positive and potentially negative consequences of information technology.